The present invention relates to a rock bolting device for drilling holes and setting bolts into the drilled holes. More particularly, it is for a rock bolter having dual feed tracks which are mounted on a turret which selectively rotates the feed tracks to a work position where they are sequentially utilized for bolt hole drilling and bolt setting.
A variety of rock bolters have been developed to drill holes and set bolts to stabilize rock walls. These rock bolters can be subdivided into single feed track and dual feed track rock bolters. U.S. Pat. No. 5,114,279 discloses a single feed shell rock bolter where a rock drill and a bolt driver are sequentially fed on to the feed track, which forms a work position for the rock drill or the bolt driver. Either the rock drill or the bolt driver, depending on which is positioned on the feed shell, can be advanced to a rock surface into which a bolt is to be set. U.S. Pat. Nos. 4,473,325 and 4,497,378 disclose a dual feed track rock bolter. One of the feed tracks directs a rock drill as it advances toward a rock surface into which the bolt is to be set, while the other feed track directs a bolt driver as it is advanced toward the rock surface to set the bolt. The dual feed tracks are sequentially rotated to a work position and, when so positioned, the rock drill or bolt driver residing thereon can be advanced to the rock surface.
All of these rock bolters employ a stinger which engages the rock surface to stabilize the track(s) on which the rock drill and/or the bolt driver resides as they are advanced to the rock surface into which bolt holes are to be drilled and into which the bolts are to be set. One of the problems with bolt setting is locating the hole which has been drilled. A centralizer is preferably employed, which swings over the hole which has been drilled to guide the bolt as it is advanced toward the bolt hole to reduce the problem of locating the bolt hole. One difficulty with these types of bolt aligning systems is that of accurately positioning the centralizer with respect to the hole into which the bolt is to be set. This problem has been overcome by employing a common stinger/centralizer that is the subject matter of U.S. Pat. No. 5,556,235, which is assigned to the assignee of the present application.
Another complicating factor in drilling holes and inserting bolts into a rock surface is that frequently the rock surface into which bolts are being set is uneven. This severely limits the ability to position the rock bolter in close proximity to the rock surface and limits the work space available for movement of components of the rock bolter which reside near the rock surface when the rock bolter is positioned to set bolts. These problems are addressed in the ""235 patent by employing a single stationary feed shell in combination with a magazine that is set back from the rock surface, which advances each bolt toward the rock surface as the bolt moves to the magazine position where it is to be picked up by the bolt driver. While this approach reduces the space required by the rock bolter in the vicinity of the rock surface, one difficulty with this approach is that the bolts are subject to transverse forces as they are advanced in the magazine, which can result in bending the bolts.
Another problem, which can occur when drilling into a friable rock, is that rock chips can fall into and impair the operation of the transfer and locking system which is used to transfer and secure the rock drill and the bolt driver on the feed track. This latter problem can be reduced by employing a turret dual feed track system such as is disclosed in the ""325 and the ""378 patents. However, the turret of the ""325 patent is designed such that the feed tracks are in close proximity to the rock surface into which the bolts are set at all times during the rock drilling and bolt setting operations. This close proximity of the feed tracks sweeps out a large area of the rock surface and would not be effective for use with uneven rock surfaces. This problem has been reduced by the ""378 patent, which teaches translating the turret along the work axis, allowing the turret to rotate when the feed tracks are more generously spaced from the rock surface. However, this additional clearance is obtained at the expense of increased complexity and increased length of the rock bolter. This increase in size complicates operation when operating in a mine shaft, and may prohibit operation in smaller shafts.
Thus, there is a need for a rock bolter that is compact and capable of readily drilling holes and setting bolts in uneven and friable rock surfaces.
It is an object of the present invention to provide a dual feed track rock bolter with a stinger/centralizer.
It is another object of the invention to provide a dual feed track rock bolter which requires a limited work space at the rock surface while maintaining a reasonably short overall length of the rock bolter.
It is another object of the invention to provide a compact dual feed track rock bolter utilizing a stinger/centralizer and employing a bolt magazine which rotates about a central magazine axis.
It is a further object of the invention to provide a supplementary stinger for a rock bolter that employs a stinger/centralizer which stabilizes the rock bolter as the stinger/centralizer is being disengaged from the rock surface.
It is still a further object of the invention to provide a drill steel retaining ring for a rock bolter employing a stinger/centralizer which focuses the motion of the drill steel tip to promote its engagement with the stinger/centralizer as the drill steel is advanced.
It is yet another object of the invention to provide a stinger centralizer which has a first head arm and a second head arm, one of which is advanced on a path where its associated head element moves along a non-linear path as it advances toward and retracts from the rock surface.
It is a further object of the invention to provide a dual feed track rock bolter having a bolt magazine which rotates about a central axis such that, when the turret is positioned with the rock drill feed track in the work position, the bolts in the magazine may be advanced into a position alignable with a bolt driver axis.
It is a further object of the invention to provide a dual feed track rock bolter having a locking mechanism to immobilize whichever of the rock drill and the bolt driver is not positioned on the work axis.
It is a further object of the invention to provide a dual feed track rock bolter having a frusto-conical bolt magazine.
It is a further object of the invention to provide a dual feed track rock bolter having bolt-engaging hands which maintain a bolt, which is initially substantially in line with the bolt driver axis, so aligned while the bolt driver feed track is swung into the work position.
The present invention, in a rudimentary form, provides a dual feed track rock bolter which has a stinger/centralizer symmetrically disposed about a work axis along which both a drill steel and a rock bolt are sequentially advanced. The dual feed track rock bolter has a drill feed track, which is traversed by a rock drill having an associated drill axis and carrying the drill steel aligned with the drill axis, and a bolt driver feed track, which is traversed by a bolt driver having an associated bolt driver axis and carrying the bolt aligned with the bolt driver axis. Both of the feed tracks are mounted on a turret which in turn is rotatably mounted to a base which also supports the stinger/centralizer. The base in turn is attached to a boom which is attached to a carrier vehicle, the boom serving to position the base and turret with respect to a rock surface into which the bolt is to be set.
The turret rotates about a turret axis which is parallel to but displaced from both the drill axis and the bolt driver axis. The turret is rotatable between a drilling position, where the drill feed track resides in a work position and the drill axis is aligned with the work axis, and a bolt setting position, where the bolt driver feed track resides in the work position and the bolt driver axis is aligned with the work axis. As designed, the rock bolter is well suited to be used in combination with a bolt magazine which positions a bolt on the bolt driver axis when the drill feed track is in the work position.
The stinger/centralizer of the dual feed track rock bolter of the present invention has a first head element, with a first head cavity and a rock engaging surface. The first head element is mounted on a first head arm which movably engages a first head arm mount which is in turn attached to the base and can be made an integral part thereof. It is preferred that the first head arm mount be located in close proximity to the boom to which the base mounts, thereby reducing the moment on the boom when the first head element engages the rock surface. The motion of the first head arm with the first head arm mount is coordinated such that the first head element traverses a curvilinear path (a path composed of one or more curved and/or linear segments) to and from an extended position. Preferably, the first head element traverses a substantially linear path. It is further preferred that the first head arm be substantially a straight arm, and it is still further preferred that the straight arm be inclined with respect to the work axis of the stinger/centralizer by between 30 and 60 degrees. This limitation assures that a substantial portion of the force transmitted is normal to the rock surface when the first head element is engaged therewith. More preferably, the inclination of the first head arm is 45 degrees with respect to the work axis.
The stinger/centralizer also has a second head element with a second head cavity, which is mounted on a second head arm which movably engages a second head arm mount which is attached to the base and can be an integral part thereof. The movable engagement of the second head arm with the second head arm mount is coordinated such that the second head element traverses a curvilinear path as it approaches and moves away from an extended position, where it can be engaged with the first head element when the first head element is in its extended position. The second head arm is crooked so as to accommodate a bolt magazine and/or movement of the turret and feed tracks therebeneath while still providing a head arm which can be readily retracted. Similarly, the path traversed by the second head element as the second head element is advanced and retracted maintains clearance of the second head element and the second head arm with respect to the bolt magazine and/or the turret and feed tracks. Providing such a path for the second head arm facilitates the construction of a compact rock bolter.
Means for advancing and retracting the first head arm and the second head arm are provided, these means include such mechanisms as linear actuators, worm gears, and rack and pinion gears.
Also provided are means for guiding the first head arm and the second head arm along prescribed paths. Preferably, these means include spaced apart arm guide surfaces positioned on the head arms. These guide surfaces can be bounding surfaces for the arms or can be walls of tracks or slots internal to the arms. Accompanying these guide surfaces on the head arms are spaced apart directing elements provided in the head arm mounts or forming an integral part thereof. These directing elements can be formed by cams or rollers mounted to the head arm mounts, or by surfaces of passages through the head arm mounts. Similarly, the attachment of the guide surfaces and directing elements can be reversed, having the guide surfaces on the head arm mounts and the directing elements on the head arms. Through the cooperative efforts of the means for advancing and retracting and the means for guiding, the first and second head elements can be moved along prescribed paths best suited for use with particular surface characteristics of the rock surface.
In many preferred embodiments, it is preferred that first head arm be substantially straight and that the prescribed path of the first head arm be a linear path. Such is readily accomplished by having the first head arm be a straight arm which slidably engages a channel in the first head arm mount, in which case the bounding surfaces of the first head arm serve as the spaced-apart reference surfaces and the sidewalls of the channel serve as the directing elements.
Such a first arm configuration finds great utility when the rock bolter is designed for drilling holes and setting bolts both into rock surfaces which are relatively flat, as well as into those which are highly irregular and have substantial variation in elevation as a function of position.
In one preferred embodiment, designed for use where the rock surface into which holes are to be drilled is substantially flat, a second arm path can be provided by forming the second head arm as an arc which slidably engages the second head arm mount so as to provide a movement of the second head element which is substantially arcuate. In this embodiment, the motion of the second head element, when in close proximity to the rock surface, has a large component of motion parallel to the rock surface.
In other applications, designed for use where the rock surface is highly irregular, the second head arm and the second head arm mount are provided with spaced apart guide surfaces and direction elements which direct the second head arm along a complex path as the second head arm is advanced. The complex path taken by the second head arm is required to provide an appropriate movement of the second head element, since the irregular rock surface makes it impractical to move the second head element along a path where a large component of the motion is parallel to the rock surface when the second head element is in close proximity to the rock surface. The second head arm is configured with guide surfaces which contact and slidably engage cams on the second head arm mount to redirect the second head arm. Preferably, the guide surfaces of the second head arm and the cams are configured such that, when the second head element is retracted away from the rock surface, the motion of the second head arm has both translational and rotational components. It is further preferred for the motion to be controlled such that the second head element is advanced and withdrawn with a substantial component of motion normal to the rock surface when in close proximity to the rock surface. Alternative configurations to provide the desired complex motion include the use of a slot in the second head arm combined with a follower or roller mounted to the second head arm mount and which rides in the slot to provide the prescribed motion. To improve reliability when used in a mine shaft environment, it is preferred to provide a degree of looseness between the spaced apart guide surfaces and directing elements, in which case the exact path traversed by the second head element will depend, in part, on the orientation of the rock bolter.
Means are provided to engage the first head element with the second head element so as to assure that the first head element mates with the second head element such that the first head cavity and the second head cavity produce a combined head cavity traversing the fully engaged head elements. The first head cavity and the second head cavity are preferably configured such that, when the first head element is fully engaged with the second head element, the resulting combined cavity has a conical guide portion and a cylindrical centralizer passage.
It is further preferred that the first head element have a first head mating surface and that the second head element have a second head mating surface, and that these mating surfaces be substantially planar so that they can be brought into sliding contact along what becomes a planar interface.
It is also preferred that a stabilizing protrusion be provided which is fixably positioned with respect to one of the head elements, and have one or more protrusion guiding surfaces which are configured to engage one or more receptor guiding surfaces which are fixably positioned with respect to the other of the head element. When such a protrusion is employed, it is further preferred that the latter raised arm have means for stabilization of the arm such that the motion of the arm at all times remains parallel to a sweep plane. The protrusion guiding surfaces and the receptor guiding surfaces preferably lie in a plane substantially parallel to this sweep plane. To maintain the integrity of the conical guide portion and the cylindrical centralizer passage of the head assembly, it is further preferred that the planar interface between the head elements lie substantially perpendicular to the sweep plane.
Another feature which is preferably incorporated into the rock bolter of the present invention is a supplementary stinger which further stabilizes the feed tracks of the rock bolter. The supplemental stinger has a stinger body, which is affixed with respect to the base, and an extendable member, which engages the stinger body and terminates in a rock-engaging end. The stinger body is preferably mounted in close proximity to the boom. When the first head arm mount is in its preferred position in close proximity to the boom, the stinger body can be attached to the first head arm mount. The supplementary stinger maintains registry of the bolt driver axis with the bolt hole as the first head arm is being retracted. This reduces the bending moment on the bolt during its final stage of setting, which occurs while the first head element is disengaged from the rock surface to allow continued advancement of the bolt. While the supplementary stinger has utility for the dual feed shell rock bolter employing a stinger/centralizer of the present invention, such also has utility for single feed shell rock bolters which employ a stinger/centralizer.
It is also preferred for the rock bolter to provide support for the drill steel when the drill steel approaches the stinger/centralizer so as to direct the drill steel into the centralizer passage. To achieve this, it is preferred to employ a drill steel retaining ring which is mounted at a proximal end region of the drill feed track, which is in closest proximity to the stinger/centralizer. The drill steel retaining ring is either mounted to the drill track or pivotable about the turret such that, in either case, the drill steel retaining ring can be axially aligned with the drill axis. The dimensions of the drill steel retaining ring are selected in accordance with the length of the drill steel, the relative separation of the drill steel retaining ring from the stinger/centralizer, and the dimensions of the combined head cavity.
When the rock drill and the bolt driver are mounted on carriages which serve to move the rock drill and the bolt driver along their respective feed tracks, these carriages can be activated by a common carrier activation means which is shared between the two carriages. The selective activation of the carriage for the tool which is aligned with the work axis (the active tool) can be accomplished by immobilizing the carrier which resides off the work axis (the non-active tool). For this reason, it is preferred that a carriage stop member be attached to the base. The carriage stop member has a drill carriage disabling surface positioned to engage the drill carriage when the drill is the non-active tool, this engagement preventing advancement of the carriage along the drill feed track. Similarly, the carriage stop member has a bolt driver carriage disabling surface positioned to engage the bolt driver carriage when the bolt driver is the non-active tool and prevent advancement of the bolt driver carriage along the bolt driver feed track. This carriage stop member provides a simple mechanism which eliminates the necessity of having two feed track advancing mechanisms.
While the stinger/centralizer described above can be employed with a variety of bolt magazines, the rock bolter of the present invention has particular utility when used in combination with cylindrical-type bolt magazines having radially arranged bolt cradles which, in combination with bolt retaining rings, maintain the bolts in position. The bolt magazine has a magazine axis which is fixably positioned with respect to the turret axis. The magazine axis is aligned such that one of the bolt cradles of the bolt magazine is axially aligned with the bolt driver axis when the turret is in or near the drilling position. The bolt retaining rings are provided with bolt exit passages which allow a bolt positioned on the bolt driver axis to be withdrawn from the bolt cradle in which it resides.
Accompanying the bolt magazine are bi-modal bolt-engaging hands which are pivotably mounted to hand arms which in turn are affixed to the turret. The bolt-engaging hands are biased to toggle between a bolt-holding position, which is assumed when the turret is in the drilling position, and a bolt driver by-pass position, which is assumed when the bolt being driven is held by the bolt driver and the centralizer and which allows the bolt driver to pass the bolt-engaging hands. The bolt-engaging hands are configured to resiliently grip a bolt that is advanced thereinto when the magazine is advanced while the turret is in the drilling position. Means for toggling the bi-modal bolt-engaging hands are provided. It is preferred that the means for toggling have a linkage pivotably connected to the bolt-engaging hands to coordinate the toggling of the bolt-engaging hands, as well as a hand-deactivating protrusion attached to the bolt driver carriage and configured to forcibly engage one of the hands when the bolt driver has advanced to a position where the bolt being held therein is engaged with the centralizer. One or more toggling ramps are provided, which are fixed with respect to the turret axis and are configured to forcibly engage one or more of the bolt-engaging hands if they reside in the bolt driver by-pass position when the turret is pivoted from the bolt setting position to the drilling position.
It is further preferred that the cylindrical bolt magazine be a tapered bolt magazine to further reduce the footprint of the rock bolter in the vicinity of the rock surface. The tapered bolt magazine is frusto-conical in overall shape, having a base radius determined by the number of bolts and the space required between the bolts to accommodate associated bolt plates, and having a top radius which is determined only by the number and diameter of the bolts. The length of the bolts defines the side of the frusto-conical shape. The tapered bolt magazine is mounted with respect to the base such that the magazine axis is inclined with respect to the bolt driver axis. The position and inclination of the bolt magazine axis is such that the magazine sequentially advances the bolts to a terminal bolt position which is aligned with the bolt driver axis when the turret is in the drilling position.